Polymerization initiator



taininfi the structure Patented Aug. 7, 1945 he OFF 5,

3 bassinet I a *PQLYMERIZATIONDYITIATOR o l William Di; Stewart; Akron; "Ohigiv, assign";

mesne assignments to TheB. F; Goodrich Company, Akron, Ohio, a corporation o'fNew York I No Drawing. Application Aug st 23, m1, Y

s i-u so. 408,1(l5 c Claimant (o recact) I This invention relates to the init tichioij olvi merization reactions, and particularly to the initiation of the ,polymerlzationof unsaturated organic compounds which are-capable oi'undergo ing addition polymerization to form ihig'h molecular weight polymers,

A nuniber'of initiators ior'such polymerization reactions are well known. In many cases, howi ever, it has been found that initiators which are eiiective at a certain pH do not function as initiators. at another pH. Thus hydrogen peroxide,

which is an eicellent initiator under alkaline con:

ditlons, cannot be employed in polymerizations efiected under acid conditions. Certain other, initiators ,can be used under acid conditions but notunder alkaline conditions.

.r haveinow discoveredthat the p tseason of unsaturated organic compounds may be initiated over a wide pH range by means of periodates. The method of this invention maybe employed n connection wit rsdfl llq n m ri fiens. of unsaturated organic compounds. wl ich, yield high molecular weight-linear polymers, whether carried out in a homogeneous systemo'rin" the form oian aqueous emulsion. Buchjunsaturated organic compounds are generally compounds containing amethylene group attached to a carbon atom by a double bond, that is, compoundsj'con'- CHFC/ One important class of soon compounds consists of monomers which contain a single oleilnic double bond present in a cap-oz group wherein at least one of the disconnected valences is connected to an electron-attracting group, that is, a group which substantially increases the electrical dissymmetry or polar character of the molecule. Well-known monomers of this class include styrene, isobutylene, acrylonitrile, methyl methacrylate, methyl acrylate, vinyl chloride, vinyl acetate, methyl vinyl ether, methyl vinyl ketone, and similar unsaturated hydrocarbons, esters, ethers and ketones. Another wellknown class of unsaturated organic compounds which contain a methylene group attached to a carbon atom by a double bond and are capable of undergoing an addition polymerization to form a linear polymer is the butadienes-l,3, by which is meant butadiene-1,3 commonly termed butap lymerize in essentially the samemanner; as: isoprene, piperylene, V 2,3-dimethyibutadiene and chloroprene. The unsaturatedorganic (com:

or potassium periodate, and ammonium periodate being-the preierred'materials. In emulsion poly-- merizations,ywater-soluble periodates should be employed. The amount of periodate employed is not critical, and may be'varied vover a wlderange from .5 or less based on the monomers to 5% or even-more. o H

As; a spec fic exampleof the use of one of the initiators of this .inventionin an emulsion-polymerization,.a mixture of55 partsby weightof butadiene and departs of acrylonitrile was acitated at 30 C. in the presence of about 250 parts of a3-% solution of myristic acid which had been 85%: neutralized withv sodium hydroxide,.0.8 part of :diisopropyl dixanthogen, andl part of "sodium periodate.v :A highyield of the copolymer in the format a'synthetlc rubber latex was obtained in listed at 30 C. in the presenceof about 250 parts 1 of a 2% solution of sodium lauryl sulfate, .01 part i of cobaltous chloride and 2 parts of sodium periodate. The polymerization was complete in 110 periodates may be catalyzed by the presence of hours, although in the absence of sodium periodate no polymerization had occurred in this lenath of time.

Polymerizations initiated with water-soluble vitamins and compounds which initiate a root diene and its homologues and analogues which formation in plants. The addition of .5 part 0! thiamine hydrochloride to the emulsion at the beginning of the polymerization in the above example, for instance, decreased the time required for the polymerization to reach completion to 45 hours. The use oi? .75 part '01 beta(indole-3- propionic acid) in a similar manner decreased the time to 15 hours.

It has been found desirable to modify the properties of butadiene polymers and copolymers by the presence during the polymerization of certain sulfur-containing compounds such as the dialkyl dixanthogens, the higher tetraalkyl thiuram monoand polysultldes, or mercapto alkyl thiazoles. These modifiers, as well as sulfur-containing alcohols and glycols such as beta-mercaptoethanol and beta-dithiodiglycol, are effective in emulsion olymerizations initiated'with watersoluble periodates. Other modifiers such as carbon tetrachloride known to be useful in connection with the polymerization of monomers such as 'methyl methacrylate may also be employed in the practice of this invention.

While homogeneous polymerizations in the presence or absence of solvents may be initiated by means of periodates, it is preferred to effect the polymerization in the form of an aqueous emulsion. when the polymerization is'efi'ected under alkaline conditions, soaps such as sodium oleate, sodium myristate and potassium palmitate may be employed as the emulsifying agent. Un-

der acid conditions, salts of organic basis containing long carbon chains such as hydrochlorid of dimethylaminoethyloleylamide, and trlmethylcetylammonium methyl sulfate may be employed. A number of synthetic saponaceous emulsifying agents including hymolal sulfates such as sodium lauryl sulfate and aryl sulfonates such as sodium isopropyl naphthalene sulfonate may be employed at any desired pH. It is an outstanding advantage of the initiators of this invention'that they may be employed in cordunction with any of these emulsifying agents at a pH best suited to the particular emulsifying agent employed.

Periodatesmay be employed in conjunction with other initiators of polymerization such as hydrogen peroxide as well as other types of initiators such as diazoamine benzene, dipotassium di- 'azomethane desulfonate, and triphenylazobenzene. The rate of polymerization may be increased by the use of catalysts for oxidation-reduction reactions such as small proportions of heavy metals salts and complexes of heavy metals with phosphates, aliphatic carboxylic acids,-or

sterols. i

The employment of other procedures known to q be useful in connection with the polymerization of unsaturated organic compounds which are capable of undergoing addition polymerization to form high molecular weight linear polymers is within the spirit and scope of the invention a defined in the appended claims.

I claim: 1. In a process or polymerizing by addition polymerization a polymerizable unsaturated organic compound which contains a methylene group at- 50 tached by an oleiinic double bond to a carbon atom in the structure 10 the polymerization to initiate the polymerization.

- 2. In a process of polymerizing in aqueous emulsion a polymerizable unsaturated organic compound which contains a methylene group attached by an olefinic double bond to a carbon atom in 15 the structure and which undergoes in aqueous emulsion an ad dition polymerization to form a high molecular weight linear polymer, the step which comprises including a water-soluble periodate in the emulsion to initiate the polymerization.

3. In a process of polymerizing in'aqueous emulsion a mixture of copoiymerizable unsaturated organic compounds which contain a methylene group attached by an oiefinic double bond to a carbon atom in the structure one of which is 'a polymerizable butadiene -l,3, the step which comprises including a watersoluble periodate in the emulsion to initiate the polymerization. Y

35 4. In a process of polymerizing in aqueous emulsion a mixture of butadiene'-l,3 and acrylonitrile. the step which comprisesaddin'g a water-soluble periodate to the emulsion to initiate the polymerization.

' 5; In a process of polymerizing in aqueous emulsion a mixture of butadiene-L3 and acrylonitrile, the step which comprises adding an alkali metal periodate to the emulsion prior to the polymerization to initiate the polymerization.

6. In a process of polymerizing in aqueous emulsion a polymerizable butadiene-1,3, the step'whlch comprises including a water-soluble periodate in the emulsion to initiate the polymerization.

WILLIAM D. STEWART. 

